Freshly harvested bok choy (Brassica rapa var. chinensis) was minimally processed and
packaged in three different kinds of plastic bags: (1) oriented polypropylene (OPP) perforated
film (10 holes, 5 mm in diameter), (2) polyethylene (PE) film with a high oxygen transmission
rate (OTR) of 3,200 ml.m-2.day-1, and (3) polyethylene (PE) film with a very high OTR of 6,000
ml.m-2.day-1. Results indicated that at 5o
C, the level of film OTR significantly affected the gas
compositions in the package headspace, and consequently the quality of fresh-cut bok choy.
The modified atmosphere created by the 3,200 OTR PE bag consisted of 3.9-4.9% CO2 and
7.8-9.9% O2
and the 6,000 OTR PE bag consisted of 2.3-3.1% CO2
and 12.3-14.8% O2
. The
atmospheres reached equilibrium after 3-4 days of storage, and they maintained this level
throughout the storage period. The perforated OPP bag showed no difference in CO2
or O2
levels when compared to the outside air, suggesting that there was no modification occurred
to the atmosphere. Changes in quality including weight loss, color (lightness, yellowness, and
hue), chlorophyll content, sensory quality, and microbial growth were least in the 3,200 OTR
PE film followed by the 6,000 OTR PE film and the perforated OPP film, respectively. The
shelf-life of fresh-cut bok choy packaged in a 3,200 OTR PE bag was 25 days, compared with
20 days in the 6,000 OTR PE bag, and only 10 days for the perforated OPP bag.